The sharp rise in the frequency of adenocarcinoma and relative decrease of squamous cell carcinoma of the respiratory and digestive systems, raises suspicion of a common element in their carcinogenetic cascade, which could result in similar trends in cell-type distribution changes of esophageal and lung cancers. The possible role of chemical irritation caused by gastroesophageal reflux disease (GERD) in non-small cell lung cancer (NSCLC) patients was investigated. There was no significant difference between the adenocarcinoma and the squamous cell carcinoma groups, neither in the composite DeMeester scores nor in any of the separate parameters of the complex score investigated. However, the ratio of detected gastroesophageal reflux cases was considerably higher than in the average population. This factor may be one element of a multifactorial cancer promotion.